1. Field of the Invention
This invention relates generally to safety pressure relief devices, and more particularly, but not by way of limitation, to a safety pressure relief device including a reverse buckling rupture disk with an improved knife means located adjacent a concave surface of said rupture disk to puncture the rupture disk upon reversal.
2. Description of the Prior Art
The prior art includes a variety of safety pressure relief devices having a reverse buckling rupture disk with a knife means located adjacent the concave side of the rupture disk.
For example, U.S. Pat. No. 3,908,684 to Short shows a reverse buckling rupture disk having a circular axially oriented cutting blade for severing a central circular portion of the rupture disk upon reversal. U.S. Pat. No. 3,294,277 to Wood and U.S. Pat. No. 3,685,686 to Raidl each show a reverse buckling rupture disk having a plurality of connected cutting blades arranged to contact the center of the concave surface of the rupture disk upon reversal so the rupture disk is impaled upon the cutting blades upon reversal. U.S. Pat. No. 3,834,580 to Ludwig et al. discloses a reverse buckling rupture disk having scores thereon with a single knife blade located adjacent the concave surface thereof the puncture the rupture disk upon reversal and cause it to split into a plurality of petals about the preformed score lines.
The present invention provides an improved cutting means which merely punctures the rupture disk upon reversal, in a manner similar to that in which a can opener is used to punch a triangular hole in the top of a beverage can. Such a puncture type rupture of the disk is preferable when only very low flow rates are required and when it is desired to minimize the chance of any material being torn from the disk and blown downstream.